of the United States. 357 



;year, changing the colors of the head only ; the young moult- 

 ing continually. Plumage silky, elastic, plentifully supplied 

 with down. Colors, including the tail, always pure white, 

 with a distinct mantle ; mantle white, pearl-gray, or deep 

 slate-black. Young mottled with dull gray and various tints 

 of brownish, confusedly spotted, passing by infinite gradations; 

 bill, feet and iris, dark ; light in the adult. 



Timid : cowardly except in defending their young. Very 

 numerous, covering whole shores. Keep generally in large 

 flocks, the young and old separate, the larger species on the 

 sea, the smaller along rivers and lakes. Alight on rocks, 

 beaches, or on the water. Walk tolerably well : swim with 

 ease ; incapable of diving. Keeping much upon the wing ; 

 flight rapid, straight, equal, long sustained, even against the 

 strongest gales. Contract their neck and draw one foot up 

 when resting. Voracious : espying and fighting against 

 their own species for prey ; attacking each other without 

 any apparent reason. Fall on and devour the wounded. 

 Patient of hunger. Feed on every kind of animal food, dead 

 or alive, fresh or putrid. Great purgators — sea Vultures; 

 the larger species prey on eggs and young birds ; but all prin- 

 cipally on fishes, of which they follow the shoals, catching 

 them with great agility on the surface of the sea, by darting 

 like an arrow, and submerging their head ; digesting scales, 

 feathers, and even putrid matter ; when irritated disgorge their 

 undigested food. Breed once a year only, principally in desert 

 places, Arctic islands, on naked rocks, or on marshy weeds, 

 with little preparation : eggs from 2 to 4, generally 3. Young 

 leaving the nest soon after exclusion, but hiding carefully, 

 and fed for several weeks by their parents. Clamorous : 

 voice loud, shrill, often repeated while flying. Flesh tough, 

 bad tasted. Feathers valuable. 



Spread all over the world. Species numerous, resembling 

 each other greatly in all their different states of plumage. 



Vol. II. 45 



